The black-and-white images show the faint emission from one of these intermediate-mass black holes. The yellow circles point to the object, which only appears in the hydrogen emission (Ha image), and not in the other colours (r-band and g-band). The green circle points to the galaxy with which the emission is associated. At the top is shown the detected emission line, with a double peak, and the outline of an accretion disc around a black hole capable of explaining the observation. Credit: Jorge Sánchez Almeida (IAC)